Attribute VB_Name = "Module2"
Public Function mccall(s, k, r, sg, t, m)
temp = 0
For i = 1 To m
randn = Application.WorksheetFunction.NormInv(Rnd(), 0, 1)
st = s * Exp((r - sg ^ 2 / 2) * t + sg * Sqr(t) * randn)
temp = temp + max(st - k, 0)
Next
mccall = Exp(-r * t) * temp / m
End Function


Public Function max(x, y)
If x >= y Then
max = x
Else
max = y
End If
End Function

Public Function mcasiancall(s, k, r, sg, t, n, m)
Dim st()
ReDim st(n)
st(0) = s
dt = t / n
temp2 = 0
For i = 1 To m
temp1 = 0
For j = 1 To n
randn = Application.WorksheetFunction.NormInv(Rnd(), 0, 1)
st(j) = st(j - 1) * Exp((r - sg ^ 2 / 2) * dt + sg * Sqr(dt) * randn)
temp1 = temp1 + st(j)
Next
temp2 = temp2 + max(temp1 / n - k, 0)
Next
mcasiancall = Exp(-r * t) * temp2 / m
End Function


Public Function jrcall(s, k, r, sg, t, n)
dt = t / n
u = Exp((r - sg ^ 2 / 2) * dt + sg * Sqr(dt))
d = Exp((r - sg ^ 2 / 2) * dt - sg * Sqr(dt))
p = 0.5
For j = 0 To n
cum = cum + max(s * u ^ (n - j) * d ^ j - k, 0) * p ^ (n - j) * (1 - p) ^ j * Application.WorksheetFunction.Fact(n) / Application.WorksheetFunction.Fact(j) _
/ Application.WorksheetFunction.Fact(n - j)
Next
jrcall = cum * Exp(-r * t)
End Function
Public Function crraput(s, k, r, sg, t, n)
Dim ft()
ReDim ft(n)
dt = t / n
u = Exp(sg * Sqr(dt))
d = 1 / u
df = Exp(-r * dt)
p = (Exp(r * dt) - d) / (u - d)
For j = 0 To n
ft(j) = max(k - s * u ^ (n - j) * d ^ j, 0)
Next
For i = n - 1 To 0 Step -1
For j = 0 To i
ft(j) = max(k - s * u ^ (i - j) * d ^ j, (ft(j) * p + ft(j + 1) * (1 - p)) * df)
Next
Next
crraput = ft(0)
End Function